Thirty-seven-year-old Wright - known as King Rat - was shot dead as he sat in a prison van outside the LVF wing of the prison near Belfast in December 1997.

At the first day of the trial of the three men accused of Wright's murder, Downpatrick Crown Court has heard that the killers had carefully planned the murder and had been able to cut a hole in a fence dividing their wing in the prison from Wright's.

Christopher McWilliams, 35, John Gerard Kennaway, 35, and John Glennon, 32, all deny the murder at Northern Ireland's top security jail on December 27 1997.

The trial could be embarrassing for Maze authorities

All three were serving sentences in the Maze for a variety of terrorist charges. McWilliams was serving life for the murder of a Belfast bar manager in 1991 and Kennaway for plotting to murder a senior Northern Ireland Conservative.

Billy Wright's murder sparked a campaign of retaliatory killings by the LVF which in turn provoked republican reprisals.

It was also a major embarrassment to prison authorities, coming less than a fortnight after a republican prisoner escaped.

The authorities are expected to be further embarrassed when their security measures come under the spotlight at the murder trial.

The three men were in the H6 block of The Maze in wings designated for the Irish National Liberation Army (INLA) when the murder took place.

Wright was being held in adjoining LVF wings, the court heard.

The opportunity for the killing arose while Wright was waiting in a van to be transported from his wing to the prison's visitors' centre, said Pat Lynch for the prosecution.

Wright: Succumbed rapidly to injuries

A hole in a fence at the rear of the wing housing the accused had been cut out and a stack of chairs put in front of it to conceal it from inspection. A portion of fencing was held in place in front of it with shoestrings, he said.

The accused went through the hole in the fence, climbed up on a flat roof and down into the courtyard where the van was waiting with Wright inside for the gates to be opened, the court heard.

Armed with two hand guns, McWilliams and Kennaway threatened the prison staff accompanying Wright, opened the side door to the van which was unlocked and singled out the loyalist leader, it was alleged.

Another LVF prisoner inside the van was told to get out of the way as they opened fire. Wright kicked out at his attackers but was shot several times and succumbed rapidly to his injuries, the court heard.

The three accused then scrambled back to their wing, where they later surrendered after negotiations with a prison chaplain and the weapons were given up, the prosecution claimed.

'Daring plan'

"This was a daring plan which depended on split-second timing but which was carried out in broad daylight with no attempt to conceal either what they were doing or their identities," said Mr Lynch.

"The murder was witnessed by prisoners and prison staff who were unable to do anything and each of the accused has been identified by witnesses."

He said there was forensic evidence, including firearms residue on the clothes of the accused, as well as blood matching Wright's on the clothing of Glennon and McWilliams.